Anti-inductive system



Oct. 14. 1924.

H.$.OSBORNE ANTIINDUCTIVE SYSTEM Filed March 4. 1920 'L 0f ATTORNEY l6 tralize t e electromagnetic PatentedOct. 1 4, 1924.

UNITED STATES PATENT OFFICE.

HAROLD S. OSBORNE, O! YORK, N. Y., ASSIGNOB T AMERICAN TELEPHONE AND TELEGBADE COMPANY, A COBPOBATION 01 NEW AHTI-INDUGTIVE SYSTEM.

Application filed larch 4, 1920. Serial No. 388,187.

To all whom it may concern.-

Be it known that I, HAROLD S. OSBORNE, residin at New York, in the count of New ork and State of New York, ave

6 invented certain Im rovements in Anti- Inductive Systems, 0 which the following is a specification.

This invention relates to anti-inductive systems, particularly to methods of and 1 means for reducing the interference from alternating current railways in telephone, telegraph or other signal conductors paralle ing the right of way.

The resent invention pro oses to neufiel of a trolle or other current supply conductor, of a rai way system by causing the return flow of the operating current through a feeder glaced closely adjacent to the trolley conuctor, and it roposes to neutralize the electrostatic field due to the voltage of the trolley conductor by impressing a substantially equal and opposlte potential on a voltage balancing wire placed closely adjacent to the said trolley conductor.

It proposes, furthermore, to diminish the effect'of any unbalance between the electroma netic fields of the trolley and retuin feeder conductors by causing the. operating 0 current to flow from opposite directions to the railway vehicle so that the unbalance due to the current from one direction is substantially neutralized by the unbalance due to the current from the opposite direc- 5 tion. The invention proposes also to sectionalize'the voltage balancing wire and to maintain each section at a potential corresponding to the. tenti'algof the adjacent portion of the tro ley conductor, so that, as

40 the voltage of the trolley wire varies from portion to portion during the travel of a railway vehicle therethrough, a proximate balance for each portion is obtained by the various sections of the voltage balancing 46 wire. It is proposed, furthermore, to sectionalize the track rails at comparatively frequent intervals in order to limit the maximum distance through which the operatin current ma flow through the track rails an 50 the groun A good understanding of the invention may now be had from the following description thereof having reference to theaccompanying drawing,"sl1owing in diaserving grammatic view one form and arrangement of apparatus emlbodyi the invention.

In this drawing re erence character A designates the tracks of a railway and B,

the conductors of a telephone, tele aph or rawing. return eeder L, placed closely adjacent, are

connected to these transformers and section-alized at the substations, so that a vehicle is limited for its supply of operating current to the adjacent substations. Feeder booster transformers M, N, O and P .are provided at intervals between substations, the primary windings of these transformers bein connected in series with the trolley con uctor K and the secondary windinis thereof in series with the return feeder these transformers'having such numbers turns in the two windings that, ideally at least, a flow of windings will cause an equal flow of current in the secondary windings. The booster transformers are designed so as not to saturate under heavy loads or even short. circuits, in order that the currents in the trolley and feeder are always substantially equal. The return feeder is connected to the tracks at points midway between booster transformers, these connections to conduct the operating current from the track rails to the return feeder. The tracks are sectionalized, for reasons explained hereinafter, by insulated 'oints placed in the track rails at points ad acent substations and feeder booster transformer locations. A voltage balancin wire R is placed closely adjacent the trofie wire K, this wire bein tions and fee er I r transformers, the sections of the wire bein supplied with potential by transformers T and U, the primaries of which are bridged acres the correspondin sections of the trolley ductor K an the return feeder L, and the secondaries of which'are connected between the said feeder L and the corresponding sections of the wire R. Those sections of the wire which are adjacent to the substations current through the primary sectionalized at t e substa- 4 and N in series to the vehicle.

' feeder to-the rails.

ing current from transformers E by flowin through minimized by reason of the H and l are supplied with potential by extra windings a on the transformers D, E, F and G. The object of the wire R is to neutralize the electrostatic effect of wire K on the signal conductors, as explained below.

When a railway vehicle V is between substations H and I, it is supplied with operat- E and F, the current from transformer E flowing through trolley conductor K and booster transformer M to the vehicle V, and the current from transformer F flowing through trolley conductor K and booster transformers P, O The current from substation H returns to transformer the rails of the sections of trac r, throu 'h whichthe vehicle V is passing, into the Feeder conductor L and the booster transformer M to the trans- H; and the ourreturns through and transformer E at the substation rent from the substation 1 the track rails, return feeder L formers N, and P into transformer The current flow in the feeder wire is sub-- stantially equal and opposite to that in the trolley wire, so that the inductive efiect onthe signaling conductors B due'to the flow of current in the one is substantially equal and opposite to that due to the flow of current in the other, provided the feeder and trolley wires are sufficiently close to-each other and substantially equal distances from the signaling conductors. Any difierence in the inductive effects of the two wires is fact that the operating current is supplied from two substations and traverses both the trolley and feeder wiresin opposite directions.

The inductive efie'ct due to a current in the supply or return conductors will-be proportional to the current times the distance which it parallels the signal circuit. If the current flowing to a given car from the two end sources were the same there would in general bean unbalance since the current from the oneend would flow parallel to the signal circuitfor a longer distance than the current from theother end. However, with the arrangement shown the currents flowing from the two sources through the respective supply branches will be to each other inversely as the distance of the car from the two sources because of the relative impedances of the branches containing conductors and boosters. In the case shown the current from the source tially three times that flowing from source F and the residual efifects therefore neutralize each other the more completely.

It will have been track rails between the wheels of thevehicle and the adjacent connection of the return Thecurrent in this part of the path 18 not as well balanced bythe F. that thereturn feeder is varies as the railway through.

E will be substannoted that part of the current path described above .consistsof the/l return feeder current flow as the part of the path whichconsists of the trolley conductor. This is all the more true because of the earth connection of the rails, by reason of which, part of the current flows through the ground instead of the rails proper. In the present invention the inductive interference of this current is minimized by the sectionalization of the track rails at comparatively frequent intervals, so that the distance through which the current flows in the track rails is small and the leakage surface between rails and round is confined to that in only one of the sections of the track, whereby the amount of ground current is reduced to a minimum.

There remains to be explained the manner in which the present invention overcomes the electrostatic interference due to the volta e of the current in the trolley wire K, vi hich voltage is not balanced by that of the current in the feeder wire L for the reason at substantially earth or zero potential because of its connections to the track rails. The voltage balancing wire R, mentioned hereinbefore,1s for this purpose maintained at a potential substantially equal and opposite to that of the trolley wire by means of the transformers S, T, V and the windings a on the transformers E and F. It will be observed that this wire is on open circuit and does not draw any power from the line; and is sectionalized, so that each section may correspond in potential toithat of the adjacent portion of the trolley wir The transformers S, T and V are preferably located adjacent the middle of their sections, so that the potential of each section of the wire is close to the average potential of the corresponding trolley section, which, of course,

' vehicle passes there- The wire B should be close to the so that its electrostatic efiect 'on conductor it? is substantially equal in magnitude to that of wire K.

Although I have hereby shown and described only one form and arrangement of circuits embodying the invention and described only one manner of practicing the same, it is readily understood that various changes and modifications may be made therein within the scope of the following claims with-out departing. from the spirit and scope of the invention.

What is claimed is:

1. In combination, a signal circuit, a'sectionalized supply-conductor ad'acent thereto for carrying current whose inductive effeet on said signaling circuit is to be neutralized, a correspondingly sectionalized return feeder conductor, a third conductor of length corresponding to the supply conductor section adjacent thereto and itself further sectionalized, and means associated with trolley conductor K said conductors to impress a potential on each section of the third conductor substantially equal and opposite to that on the corresponding portion of the supply conductor section.

2. In combination, a signal circuit, a sectionalized supply conductor adjacent thereto for carrying current whose inductive effeet on said signaling circuit is to be non-- tralized, a correspondingly sectionalized return feeder conductor, a third conductor of length correspondingto the supply conduc-i to each other, booster transformers havin one of their windings in series with one o said'conductors and another winding in series with the other of said conductors, connections between the track rails and said feeder conductor substantially midway between said booster transformers, means adjacent said booster transformers for dividing said rails into sections, a voltage neutralizingconductor placed close to said trolley conductor, and means for im ressing on said neutralizing conductor a V0 tage equal and opposite to said trolley conductor.

4. Ir a system for minimizin the interference effect due to the propulslon'currents of an. electric railway in a signal conductor parallel to the right of way, a current supply conductor, a return feeder conductor placed closely adjacent thereto, means for dividing said conductors into sections insu-. lated from each other, a current supply source for said conductors adjacent the end of each section, booster transformers located at intervals in each section of said conductors for rendering the flow of current in one substantially equal and o posite to that in the other, means for insu ating the track rails at the ends of each'section of the said conductors and at booster transformer locations, means for connecting the return feeder conductor to the track rails adjacent the niidpoints of the track sections, a voltage balancin wire closely adjacent to said current supp y conductor, said wire bein divided into a plurality of sections for eac section of the supply conductor, and means for maintaining each section of said wire at a potential substantially equal and opposite to that of the adjacent portion of the supply conductor. I

5. In combination, a railway track, a trolley and feeder conductor closely adjacent to each other, booster transformers havin one of their windings in series with one 0 said conductors and another winding in series with another of said conductors, connections between the track rails and said feeder conductor substantially midway between said booster transformers, means adjacent said booster transformers for dividing said rails into sections, a voltage neutralizing conductor placed close to said trolle 'conductor, and a transformer associated wlth said conductor for impressing on said neutralizmg conductor a voltage equal and opposite to said'trolley conductor.

In testimony whereof, I have slgned my name to this specification this 2n day of March, 1920.

v HAROLD S. OSBORNE. 

